Hair dye is generally classified into four types, namely, oxidative hair dye, ionic hair dye, temporary hair dye, and others. Among these hair dyes, an oxidative hair dye, which has been most widely used at present, is also referred to as a permanent hair dye, and it is mainly constituted with paraphenylenediamine or para-aminophenol that becomes an active reaction intermediate as a result of oxidation by hydrogen peroxide. The active intermediate then reacts with a dye coupler molecule in hair, and it changes to a shampoo-resistant hair dye. However, such an oxidative hair dye damages hair, may cause contact dermatitis or latent influence on total body for a long period of time, and may be suspected as mutagenicity or carcinogen. An ionic hair dye is also referred to as a semi-permanent hair dye, and it does not damage hair. However, such an ionic hair dye is problematic in term of skin coloration upon dyeing, and in that the dye is washed off from hair by performing shampooing operations four to ten times. A temporary hair dye does not damage hair, and skin coloration is overcome since washing is possible. However, such a temporary hair dye is washed off from hair by performing a single shampooing operation.
As another hair dye, there has been proposed a non-oxidative hair dye containing polyvalent phenol and an iron salt (Patent Documents 1 to 3). However, previous non-oxidative hair dyes have not been satisfactory in terms of hair dyeing property and color tone. The non-oxidative hair dyes which are currently available are only the products, base material of which is cream (emulsion).
Moreover, Patent Documents 4 and 5 disclose that the hair dye compositions which comprise a polymer containing flavan-7-ol as an essential constitution monomer may contain multivalent metal salt, xanthane gum and benzyl alcohol, but these hair dye compositions do not contain tannic acid. Also, Patent Document 6 discloses a hair dye tool where comb portion is fit to an aerosol container which contains a hair dye, and discloses that the hair dye may contain benzyl alcohol, xanthane gum, metal salt and tannic acid. However, this hair dye is not a hair dye of two-agent type. Patent Document 7 discloses a cosmetic for head hair which contains fine powders of henna plant which were pulverized into a diameter of 2 mm or less, or henna extract, wherein the cosmetic contains an antioxidizing agent, dye for hair and other various components. However, this hair dye is not a hair dye of two-agent type.